BI8.1-6 | Vitamins and Nutrition — Glossary

An organic micronutrient required in small amounts for normal metabolism that the body cannot synthesise in adequate quantities and must obtain from the diet

Vitamins A, D, E, and K; absorbed with dietary fat, transported by lipoproteins, stored in liver and adipose tissue; can accumulate to toxic levels

The alcohol form of vitamin A; the transport form in blood (bound to retinol-binding protein); interconverts with retinal; found in animal foods (liver, eggs, dairy)

The aldehyde form of vitamin A; the chromophore of visual pigments (11-cis-retinal in rhodopsin and iodopsin); essential for the visual cycle

The acid form of vitamin A; acts as a nuclear hormone binding RAR/RXR receptors to regulate genes for cell differentiation, epithelial integrity, and embryonic development

The spectrum of ocular manifestations of vitamin A deficiency, ranging from night blindness to Bitot's spots to corneal xerosis to keratomalacia (irreversible blindness)

Foamy white-grey patches on the conjunctiva caused by keratinised epithelial metaplasia in vitamin A deficiency; a pathognomonic clinical sign

1,25-dihydroxyvitamin D3, the hormonally active form of vitamin D; synthesised in the kidney by 1-alpha-hydroxylase; promotes calcium absorption in intestine and bone mineralisation

A childhood disease caused by vitamin D deficiency resulting in defective mineralisation of growth plates; features include bowed legs, rachitic rosary, craniotabes, and widened wrists

The adult equivalent of rickets; defective mineralisation of mature bone causing bone pain, proximal myopathy, and pathological fractures; Looser zones on X-ray

The most biologically active form of vitamin E; a chain-breaking antioxidant that prevents lipid peroxidation of polyunsaturated fatty acids in cell membranes

The vitamin K-dependent post-translational modification that converts glutamate to gamma-carboxyglutamate (Gla) residues in clotting factors (II, VII, IX, X) and proteins C and S

An anticoagulant drug that inhibits vitamin K epoxide reductase (VKOR), blocking the regeneration of reduced vitamin K and preventing gamma-carboxylation of clotting factors

The active coenzyme form of vitamin B1; cofactor for pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase, branched-chain keto acid dehydrogenase, and transketolase

Niacin (vitamin B3) deficiency disease characterised by the 4 Ds: Diarrhoea, Dermatitis (photosensitive, Casal's necklace), Dementia, and Death if untreated

The active coenzyme form of vitamin B6; cofactor for over 100 enzyme reactions including transamination, decarboxylation, and ALA synthase in haem synthesis

The active coenzyme form of folic acid; carries and transfers one-carbon units needed for purine synthesis, thymidylate synthesis, and methionine regeneration

One of two active coenzyme forms of vitamin B12; cofactor for methionine synthase, which converts homocysteine → methionine and regenerates THF from methyl-THF

The concept that in B12 deficiency, folate becomes trapped as methyl-THF (cannot regenerate THF), causing functional folate deficiency and impaired DNA synthesis

An anaemia characterised by large abnormal red cell precursors (megaloblasts) in bone marrow due to impaired DNA synthesis; caused by B12 or folate deficiency

Demyelination of the posterior columns (loss of vibration and proprioception) and lateral corticospinal tracts (UMN signs) of the spinal cord; specific to vitamin B12 deficiency

A glycoprotein secreted by gastric parietal cells that binds vitamin B12 in the duodenum; the B12-IF complex is absorbed in the terminal ileum; absence causes pernicious anaemia

A water-soluble vitamin that functions as a reducing agent; essential cofactor for prolyl and lysyl hydroxylases in collagen synthesis; also aids iron absorption and is an antioxidant

Weight in kg divided by height in metres squared; used to classify nutritional status; Asian/Indian cut-offs are lower than WHO cut-offs due to higher metabolic risk at lower BMIs

Low height-for-age (Z-score <-2 SD); reflects chronic undernutrition; affects 35.5% of Indian children under 5 (NFHS-5)